Patent GB-668737-A (GB)
Title: Method of measuring and controlling the temperature of an open hearth furnace roof and similar objects
IPC: G01K1/14
Filed: 1949-09-05
Abstract: 668,737. Photo-electric pyrometers. TINSLEY (INDUSTRIAL INSTRUMENTS), Ltd., and STEGHART, F: L. F. Aug. 29, 1950 [Sept. 5, 1949], No. 22985/49. Class 40 (iii). [Also in Group XX] A mounting for a photo-electric pyrometer comprises a holder 4 into which the pyrometer can be inserted axially and quick-release locking means operable by relative rotation between the pyrometer and a part of the holder. The outer end 1 of the pyrometer is secured by screws 2 to a handle 3 and after axial insertion, rotation of the pyrometer allows bayonet lugs 5 on the holder to enter apertures 6 in the side limbs 3a of the handle. A pair of spring-pressed plungers 7 are forced upwardly by chamfered edges on the forward ends of the lugs until the plungers, entering recesses 5b in the lugs retain them in the locking position. A cross-bar 9 is provided for releasing the plungers 7. The holder may have a water jacket W. In a modification a coarse four start interrupted thread on the pyrometer body engages corresponding threads on the inside of the holder, a spring- loaded detent plunger being mounted on the end of the holder to engage a recess in the pyrometer end. In a further embodiment a peripheral recess in the pyrometer is engaged by a spring-loaded latch member pivoted to the holder. In another form one or more clips pivoted to the holder may be swung over the edge of the end plate of the pyrometer after the latter has been pushed home, spring-loaded detents being provided for preventing accidental release. In a further embodiment a clamping- bar pivoted at one end to the holder may be swung across the pyrometer end and secured by a wing-nut on a bolt projecting from the holder. The photo-electric pyrometer may have a nozzle at its end in the furnace cooled by an air blast, the latter also preventing ingress of hot metal particles. The object lens is mounted in a cell which may be removed for cleaning. A retaining ring keeps the cell in position and also acts as a front bearing for the pyrometer when the latter is inserted in a calibrating unit. A barrier layer photo-cell is mounted in an insulated carrier on the forward end of which are carried the four leaves of an iris which act as a field stop, the iris being opened and closed by rotating the cell carrier. Small pins passing through the iris leaves engage in a spiral scroll of fine pitch so that the cell holder requires two revolutions for the full range of iris adjustment. Access to the screwdriver adjustment for the iris is blocked by the electrical connector between the pyrometer and its associated cable. The pyrometer may be checked by substituting a disappearing filament pyrometer in the same holder and focusing on the same part of the steel furnace roof. The water jacket may have a mounting flange for insertion in place of the photo-electric pyrometer to enable a disappearing filament pyrometer to be sighted on the furnace roof. Alternatively a fitting similar to a telescope with or without lenses may be used to focus the pyrometer body on to selected spots. A small spotlight may be focused on to the roof through the water jacket.